Brain Training May Help Clear Cognitive Fog Caused by Chemotherapy

Why It Matters

Disease, medical treatment, and aging can all cause mental decline.

Brain calisthenics: A Lumosity user plays an online game.

Cancer survivors sometimes suffer from a condition known as “chemo fog”—a cognitive impairment caused by repeated chemotherapy. A study hints at a controversial idea: that brain-training software might help lift this cognitive cloud.

Various studies have concluded that cognitive training can improve brain function in both healthy people and those with medical conditions, but the broader applicability of these results remains controversial in the field.

In a study published in the journal Clinical Breast Cancer, investigators report that those who used a brain-training program for 12 weeks were more cognitively flexible, more verbally fluent, and faster-thinking than survivors who did not train.

Patients treated with chemotherapy show changes in brain structure and function in line with diffuse brain injury, and they often report long-term cognitive effects, says Shelli Kesler, a Stanford University clinical neuropsychologist who led the research. The new study “suggests that cognitive training could be one possible avenue for helping to improve cognitive function in breast cancer survivors treated with chemotherapy,” she says.

The results may not convince everyone. “One of the biggest challenges in the cognitive training world is to show an effect that generalizes to real-world functioning,” says Susan Landau, a neuroscientist at the University of California, Berkeley. Several companies offer commercial cognitive training programs that promise improvements in memory, attention, mental agility, and problem-solving skills. The appeal is clear, says Zach Hambrick, a psychologist at Michigan State University in East Lansing, but whether they have lasting general effects is not.

The fact that companies are marketing these training programs to customers before their value has been rigorously proved has caused some skepticism in the field, say experts. “The field is still growing,” says Suzanne Jaeggi, a neuropsychologist at the University of Maryland. While studies have shown that there are cognitive benefits to the training, it’s very hard to detect an impact on daily life, she says. However, some work, including research by her own group, has shown that working memory exercises can improve reading abilities in schoolchildren.

In the study conducted by Kesler and colleagues, the participants trained at home on Lumosity, a collection of gamelike cognitive exercises developed by Lumos Labs in San Francisco. (Lumos Labs did not fund the study.)

Kesler’s project is one of around two dozen efforts using Lumosity software to study human cognition. With 35 million customers worldwide, Lumosity is collecting what it says is the world’s largest database of human cognition, which could be queried for connections between lifestyle and cognitive ability. “Our technology collects a lot of data and makes it easy to run experiments to learn more generally about human cognitive performance,” says Mike Scanlon, cofounder of Lumos Labs. “We track all of the results from the cognitive testing and training, and we can combine that with demographic information to learn about how people’s cognitive performance changes and develops over the years.”

One such finding, he says, is a correlation between outside weather temperature and cognitive performance: “It turned out that the colder it is, the higher people’s performance is, even though generally they are inside doing this on a computer.”

Most of the scientific projects involving Lumosity’s software are exploring the effectiveness of brain training in different populations, from schoolchildren to stroke patients. For the study on breast cancer survivors, 41 women aged 40 and older, who were at least a year and half past their last chemotherapy treatment, were tested on several cognitive tasks at the beginning of the study. Then half the women used Lumosity training modules for 20 to 30 minutes four times a week for 12 weeks, and all were tested again.

When the investigators tested the participants in verbal memory, processing speed, and cognitive function, they found that the women who had used the brain training program improved in three of five objective measures.

“This is a well-done study—they had not just one transfer test but several,” says Hambrick, who notes that many studies of cognitive training depend on a single test to measure results. “But an issue is the lack of activity within the control group.” Better would be to have the control group do another demanding cognitive task in lieu of Lumosity training—something analogous to a placebo, he says: “The issue is that maybe the improvement in the group that did the cognitive training doesn’t reflect enhancement of basic cognitive processes per se, but could be a motivational phenomenon.”

Even if the effects are due to motivation or some other benefit not related to mental agility, that’s still useful, says Landau. “If [cognitive training] is something that makes people feel good and improves their confidence in their own skills, that’s not trivial at all,” she says. “That could be a big part of the effect that’s observed.”